Stencil drive mechanism for automatic sewing and the like machines



May 13, 1969 Filed Feb. 14, 1967 E. BECKER .ETAL

STENCIL DRIVE MECHANISM FOR AUTOMATIC SEWING I AND THE LIKE MACHINES Sheet of3 A Tree/vs May 13, 1969 E. BECKER ET AL 3,443,445

STENCIL DRIVE MECHANISM FOR AUTOMATIC SEWING AND THE LIKE MACHINES Sheet 2 of 5 Filed Feb. 14, 1967 fill/II 5 H7 1 May 13, 1969 E. BECKER ET AL 3,443,445

' STENCIL DRIVE MECHANISM FOR AUTOMATIC SEWING AND THE LIKE MACHINES Filed Feb. 14, 1967 Shegt 3 of s A TfOPA/E Y United States Patent 3,443,445 STENCIL DRIVE MECHANISM FOR AUTOMATIC SEWING AND THE LIKE MACHINES Ernst Becker, Darmstadt, Karl Notz, Kulmbach, Upper Franconia, and Karl-Heinz Meier, Zeilhard uber Darmstadt, Germany, assignors to Quick-Elektromotoren- Werk G.m.b.H., Darmstadt, Germany, a corporation of Germany Filed Feb. 14, 1967, Ser. No. 615,996 Claims priority, application Germany, Feb. 15, 1966,

Int. Cl. F16h 37/08, 25/08, 25/16 US. Cl. 7455 11 Claims ABSTRACT OF THE DISCLOSURE A stencil drive mechanism comprises a stencil strip having straight and at least one bent section, a driving roller engaging the concave side of the stencil, and a guide roller engaging the convex side of the stencil and arranged with its axis parallel to and rotatable concentrically with the axis of the driving roller. Both rollers are positively driven in opposite directions by one sun gear and the planetary carrier of a differential drive whose remaining sun gear is driven by a power source, to displace the stencil by said rollers.

The present invention relates to automatic sewing path or pattern copying and the like .devices or machines of the type comprising a sewing goods tentering or the like work supporting frame displaceable within the plane of the sewing pattern to be produced, a control stencil displaceable within a plane coinciding with or parallel to said first plane and operably connected with said frame, said stencil including a guide strip having a configuration conforming with said sewing path and being driven by a stationary driving roller engaging one side of said strip and a guide roller engaging the opposite side of said strip, said guide roller being disposed opposite to said driving roller and rotatively displaceable within an arcuate path concentric with said driving roller.

In arrangements of the foregoing type, the driving roller is in rolling engagement with the stencil guide strip, whereby to displace the stencil in a plane preferably parallel to the plane of the sewing path or seam to be produced upon the sewing goods or fabric operated on. The stencil being coupled, through a cross-slide or the like mechanism, with the sewing goods tentering frame displaces the latter along the desired sewing path, in a manner well known in the art of automatic sewing path copiers or machines of this type. A requirement for the satisfactory operation of sewing path copiers of the foregoing type is that the driving roller and the stencil guide strip be maintained in continuous mutual coupling or friction engagement by a force acting at right angle to the tangent of said strip at the instantaneous engagement points, since otherwise a jerky and non-uniform stencil movement will be the result, or jamming or complete stoppage of the stencil may occur at an intermediate point of the sewing path or pattern.

The foregoing conditions and requirements can be readily fulfilled in the case of relatively slightly curved sewing paths or sections. In such a case, the guide roller, being displaceable within an arcuate path concentric with the driving roller, automatically adjusts itself relative to the latter, in such a manner as to cause the plane including the axes of both rollers to be at a right angle to the tangent of the stencil guide strip at any position of said roller in relation to said strip, or throughout the entire stencil path or operation. The smaller the radius of curvature of a non-linear or bent portions of the sewing path, the more difficult becomes the readjustment of the guide roller relative to the driving roller and stencil in the manner pointed out.

Accordingly, an important object of the present invention is the provision of improved stencil drive mechanism of the referred to type which is substantially devoid of the foregoing and related drawbacks and defects inherent in the prior art devices of similar and related character.

A more specific object of the invention is the provision of stencil drive mechanism of the referred to type which both simple in construction as well as efficient in operation and which will ensure a smooth and reliable stencil operation, substantially independently of the radius of curvature of consecutive stencil sections or portions, varying practically between zero and infinity, or sharp edges and linear stencil configuration, respectively.

The invention, both as to the foregoing and ancillary objects as novel aspects thereof, will be better understood from the following detailed description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings forming part of this specification and in which:

FIG. 1 is a side elevational view of a. complete automatic sewing path copying machine embodying a control stencil and suitable for use in conjunction with the improved stencil drive mechanism according to the invention;

FIG. 2 is a diagrammatic plan view of a control stencil and driving and guide roller therefor, the latter being shown in various relative positions to said stencil, explanatory of the function and operation of the invention;

FIG. 3 is a vertical sectional view showing the driving roller, stencil guide, guide roller and a single-differential drive according to the invention, suitable for the operation of a stencil of the type shown by FIG. 2;

FIG. 4 is a top view showing the driving unit of the differential drive of FIG. 3;

FIG. 5 is a view similar to FIG. 3, embodying a twindifferential drive constructed in accordance with the principles of the invention;

FIG. 6 is a top view showing the drive unit of the twin-differential of FIG. 5; and

FIG. 7 is a diagrammatic plan view of a control stencil suitable for use in conjunction with the twin-differential drive according to FIG. 5.

Life reference numerals denote like parts and elements throughout the different views of the drawings.

With the foregoing objects in view, the invention involves generally the provision of a sewing path copying or the like machine of the referred to type, wherein the rotary motions of the driving roller about its own axis and of the guide roller of the control stencil about an axis concentric with said driving roller are derived, respectively, from two output members of a differential drive rotating in opposite direction, with the remaining drive member serving as an input continuously driven by a suitable source, such as the electric motor of a sewing machine or a special stencil drive motor, respectively. The differential drive may be in the form of a planetary gearing or known construction, including a pair of sun gears and a planetary carrier rotatively supporting a number of planet gears in meshing engagement with both said sun gears, one of said sun gears serving as the driving or input member and the remaining sun gear and planetary carrier being operably connected, respectively, with the driving and guide rollers of the stencil.

As a consequence, the stencil guide roller, in the case of the present invention, is positively driven, in addition to the driving roller, selectively and intermittently, whenever the curvature of the stencil causes a braking or stoppage of the driving roller, due to the operation of the differential drive of the type described in enabling rotary motion to be transmitted between any two of the drive members by braking or locking of the third member. On the other hand, as soon as the guide roller, in passing around a bent or curved section of the stencil, reaches a position of the plane including the axis of the driving and guide rollers being normal to the tangent of the stencil, rotation of the guide roller is again interrupted, whereby to enable the driving roller to assume its full rotating speed. As a result of this mutual interaction between the driving and guide rollers, both being positively driven by the input member of the differential drive, the stencil is prevented from slipping or jamming, independently of the degree or radius of curvature of the sewing path or sections thereof, or variations of the curvature between practically zero and infinity. In other words, it is possible, by the use of the present invention, to automatically sew a pattern including extremely sharp bents or edges efficiently and reliably.

According to a preferred embodiment of the invention, the differential drive takes the form of a concentric planetary gearing of known construction including an outer sun gear, an intermediate planetary carrier and an inner sun gear, with the stencil, driving roller being operably connected with the planetary carrier, with the rockshaft rotating the guide roller operably connected with the inner sun gear, and with the outer sun gear forming the input of the drive of the stencil. An especially compact embodiment is obtained by the use of a drive shaft operating the driving roller in the form of a hollow shaft and of a rockshaft concentrically mounted within said hollow shaft.

'In order to maintain a proper operating pressure between the stencil and driving roller, the guide roller is advantageously spring-biased in the direction towards the driving roller. For this purpose, the rockshaft operating the guide roller may be fitted with a single-arm guide lever or member having a radial slot wherein is mounted a spring-urged guide block rotatively supporting the guide roller. Alternatively, the rockshaft operating the guide roller may be fitted with a double-arm lever or member to which is yieldingly connected, through a flat spring or the like, a supporting member in turn rotatively supporting the stencil guide roller, in a manner as will become further apparent from the description in reference to the drawings.

In order to enable a selective sewing in one or the other direction of the sewing path, the rotating direction of the input shaft of the differential drive may be reversed, such as by the provision of a pair of oppositely driven magnetic clutches having output members fast on the drive shaft connected to the input member of said drive.

The differential drive is advantageously coupled with its operating source through a worm gear drive which, aside from effecting a desired speed reduction, acts as a brake in preventing undesired rotation of the input shaft of the differential drive in its inoperative condition. Besides, the stencil may be driven, via suitable motiontransmitting means and the differential drive, either by its own driving motor or by way of the main driving motor of a sewing or the like machine.

Furthermore, the rockshaft operating the stencil guide roller is advantageously fitted with a braking magnet which serves to arrest said shaft during the interruptions of the stencil drive. In this manner, the rockshaft will be automatically arrested in a predetermined position, whereby to dispense with any manual adjustment of same.

According to a further improved feature of the invention, the stencil drive is automatically connected and disconnected by means of an electric control switch controlled by the stencil. For the latter purpose, the rockshaft of the stencil guide roller may be in the form of a hollow shaft having mounted therein and in axially displaceable relation thereto a switching rod which has one end disposed in operative connection with the actuating member of said switch and which has its opposite end connected to a follower element resiliently engaging the edge of the stencil formed with suitable cam sections for cooperation with said element.

The driving roller is advantageously fitted with a ringshaped conical lower flange engaged by the lower edge of the strip-like stencil, to serve as a guide for the stencil in cooperation with said follower element, in the manner shown in greater detail by the drawing and further described in the following.

In order to deal with sewing paths having bents or portions of curvature extending in both directions from the path, there may be employed, according to a further improved feature of the invention, a pair of axially displaced coaxial driving rollers each having associated therewith its own guide roller, one of said driving rollers cooperating with sections or component portions of said path corresponding to curvatures in one direction and the other driving roller cooperating with separate components of the stencil having curvatures extending in the opposite direction from said path.

In an arrangement of the latter type, the two driving rollers and associated guide rollers may be advantageously driven by the units of a special twin-differential drive mechanism. According to a simplified construction of a device of the latter type, the two guide rollers being displaced by are disposed at equal distances from the rotary axis of the associated driving rollers and operably connected with a common rockshaft controlling both guide rollers, said rockshaft and the two driving rollers being driven by the respective output members of the twin-differential drive mechanism. The latter may advantageously consist of a coaxial twin-planetary gear drive, the planetary carriers of which are connected with the separate driving rollers and the inner sun gears of which are coupled with the common rockshaft for the operation of the stencil guide rollers. In addition, said rockshaft may be utilized for the operation of auxiliary devices, such as a thread cutting knife operably connected therewith through a chain drive or the like mechanism.

Referring more particularly to FIG. 1, the automatic sewing path copier shown comprises a stationary conventional sewing machine 2 mounted upon a sewing or work table 1 for cooperation with a sewing goods supporting or tentering frame 4 displaceable upon the table 1 relatively to the stitching tools or needle 3 of said machine, for the automatic sewing of a seam or path of desired shape or configuration. For the latter purpose, the tentering or supporting frame 4 is operably connected, through suitable connecting or coupling means 5, preferably in the form of a cross-slide mechanism, with a control stencil 6 also displaceable upon the table 1 and having a configuration conforming with the seam to be sewn upon the sewing goods or fabric, in the manner shown and described in greater detail by copending patent application Ser. No. 603,303, filed by the present joint applicants Ernst Becker and Karl Notz on Dec. 20, 1966, entitled Automatic Sewing Path Copying Device for Sewing and the Like Machines. The disclosure of said prior application is, therefore, embodied in the instant application by reference for further details regarding the stencil and sewing goods frame coupling mechanism and operation of the automatic sewing path copier forming the subject of the present invention.

More specifically, in the example shown, the control stencil 6, as more clearly shown by FIGS. 2 and 3, has the form of an upstanding strip or rail 8 conforming with the sewing path or pattern 7 to be sewn and being mounted upon a base or plate 9, said strip advantageously coinciding with the edge of a corresponding recess 10 in the plate 9, as shown in FIG. 2.

Operation or displacement of both the stencil 6 and tentering frame 4 coupled therewith is effected according to the present invention by a stencil drive mechanism 12 as shown in greater detail by FIGS. 3 and 4. Accord ing to the embodiment shown by the latter figures, the stencil drive includes its own electric driving motor 13, FIG. 4, which drives an input bevel gear 14 meshing with two output bevel gears 16 and 17 which are rotatively mounted upon a worm shaft carrying a worm 25, gears 16, 17 being in turn connected, respectively, each with one of the input coupling halves or members 18 and 19 of a pair of magnetic clutches or couplings 20, 21, the output coupling halves or members 22 and 23 of which are fast upon the worm shaft 15. Meshing with the worm 25 is a worm gear 27, said shaft being further fitted with a braking magnet 26 of known construction.

The worm gear 27 is in turn rotatably mounted upon a hollow vertical shaft 28, hereinafter referred to as the oscillating or rockshaft of the stencil drive mechanism. Connected to the worm gear 27 is the outer sun gear 29 forming part of a dilferential or planetary gear drive 30 and being also rotatably mounted upon the rockshaft 28. Sun gear 29 meshes with a number of planet gears 31 which in turn mesh with an inner sun gear 32 of the differential drive 30, said inner sun gear being fast upon the rockshaft 28. The planetary gears 31 are freely rotatably mounted upon a planetary carrier 34 which is rigidly connected with a further hollow drive shaft 35 concentric with and mounted upon the rockshaft 28.

Rockshaft 28 and drive shaft 35 encircling the same are passed through a vertical bore in the work table 1, the upper end of the shaft 35 being connected to a stencil drive roller 37 which is in frictional driving engagement with one side of the stencil strip 8 adjoining the recess 10, FIG. 2, said strip resting at its lower end upon a conical extension 38 of the roller 37. In other words, the driving roller 37 engages the concave side of the stencil strip 8 and the guide roller 44 engages the convex side of the strip in respect to the bents 65 and 69. Rigidly connected to the end of the rockshaft 28 projecting above the drive roller 37 is a rotary or lever slide or guide member 40 provided with a radial slot 41 in which is slidably mounted a guide block 42. The latter has a depending pin or shaft upon which is freely rotatively mounted a stencil guide roller 44 engaging the side of the stencil 8 opposite to the driving roller 37. Guide 40 is furthermore provided with a radial bore 45 communicating with the slot 41 and serving to enclose a coiled spring 46 having one end engaging the side of the slide block 42 opposite to the rockshaft 28 and having its opposite end engaging an adjustable set screw 47 mounted in the bore 45.

Passing centrally through the rockshaft 28 is an axially displaceable switching rod 50 which has its upper end connected to a flat spring 51 secured to the underside of the guide 40 and having its end resiliently engaging the upper edge of the stencil or guide strip 8. The lower end of the rod 50 rests upon the actuating lever 52 of an electric switch, preferably in the form of a microswitch 53, connected in the circuit of the stencil drive motor 13, FIG. 4. The lower end of the rockshaft 28 is fitted with a further braking magnet 60.

In use, the stencil drive mechanism described in the foregoing operates as follows with reference being had to FIGS. 2-4. To begin with, the end of the guide strip 8 of the stencil 6 is inserted between the drive roller 37 and the guide roller 44, a possible starting position being shown at 62 in FIG. 2. According to the latter, rollers 37, 44, on the one hand, and the stencil 6, on the other hand, are shown, in the interest of simplicity of illustration, as if the roller pair 37, 44 were displaced along the stationary strip 8, this being the equivalent of the actual relative motion between the stationary roller pair 37, 44 and driving of the strip 8, to displace the stencil along a path conforming with the sewing path 7 to be copied.

The flat spring 51 engages, in the starting position of the stencil 6, a depression or recess in the upper edge of the guide strip 8 and, upon further slightly manually advancing the stencil, spring 51 will engage the upper edge of the strip 8, thereby lifting the switching rod 50.

As a consequence, switch 53 is closed and the motor 13 started to rotate, while the braking magnets 26 and 60 are in their open or inoperative position. Besides, closing of the switch 53 results in the energization of the magnetic clutch or coupling 20. As a consequence, worm 25 drives, via worm gear 27, the sun gear 29 of the diiferential drive 30, causing thereby gear 29 to rotate in anticlockwise direction in the example shown and described. Coil spring 46 acts to maintain a close engagement or predetermined frictional pressure between the rollers 37, 44 and the stencil or guide strip 8. As a consequence, rollers 37, 44 will assume a position of minimum spacing distance between their rotary axes, or with the plane including said axes including a right angle with the plane or tangent of the strip 8 or sewing path 7, respectively.

The initial section 63 of the stencil guide strip 8, FIG. 2, is shown to follow a straight line, whereby to prevent rotation or locking motion of the guide roller 44 about the axis of the drive roller 37 and to in turn lock the rockshaft 28 and inner sun gear 32, while enabling the planet gears 31, together with the planetary carrier 34, to rotate in anti-clockwise direction and to drive the drive roller 37 via the drive shaft 35.

As is well known, in a planetary or differential drive of the type shown and described and comprising essentially a pair of sun gears forming two component members of said drive and a number of planet gears meshing with both said sun gears and being rotatively mounted upon a planetary carrier forming the third component member of said drive, locking or arresting of any of said members will enable rotary motion to be transmitted between the remaining members, this operation and function of the planetary or differential drive being utilized, in cooperation with the special stencil drive mechanism according to the present invention, to effect or maintain a smooth and positive stencil control or operation, substantially independently of changes or variations of the radius of curvature of the stencil or sewing path configuration, varying between zero and infinity, in a manner as will become further apparent as the description proceeds.

After passing the intermediate position 64, the roller pair 37, 44 reaches the first bent 65 of the sewing path or pattern 7. As a consequence, the drive roller 37 is arrested or prevented from further displacement at this position, whereby to arrest or lock the planetary carrier 34. Due to the continued rotation of the outer sun gear 29 by the motor 13, the inner sun gear 32 driving the rockshaft 28 is now caused to rotate, whereby to in turn deflect or displace the guide roller 44 in clockwise direction in relation to the shaft 28, that is, from its position 66 to the position 67 according to FIG. 2. Upon reaching of the latter position, the drive roller 37 is released, while the rockshaft 28 is again locked, whereby to enable the continued advance or displacement of the stencil along the path 7.

The same mutual displacement or operation between the drive roller 37 and rockshaft 28, or guide roller 44, is repeated at the bent 69 of the sewing path 7. Upon finally reaching the end position 70 of the path, FIG. 2, by the roller pair 37, 44, the flat spring 51 again engages a depression or cutout in the edge of the guide strip 8, whereby to cause the switching rod 50 to be displaced in the downward direction and to operate the switch 53, resulting thereby in the stoppage of the motor 13 and in turn of the stencil operation.

By the energization of the magnetic clutch 21 in place of the clutch 20, the direction of rotation of the worm 25 and sun gear 29 may be reversed for the operation of the stencil or guide strip 8 in a direction opposite to that described hereinbefore. Such an operation may, for instance, be desirable where an idle return movement of the stencil 6 from the position 70 to the position 62 is to be dispensed with or where a seam is to be sewn during the next following sewing cycle in the reverse direction, after exchanging the sewing goods frame 4.

As shown by FIG. 2, the sewing path 7 corresponds to the trace of the axis of the drive roller 37 relative to the guide strip 8. By suitably bending the strip 8, such as at the corners or points and 69, that is, with the radius of curvature corresponding to the outer diameter of the drive roller 37, it becomes possible by the use of the present invention to sew a path or pattern having bents or corners with a radius of curvature of practically any value, including zero or corresponding to sharp bents and infinity or corresponding to straight stencil portions, respectively. According to a preferred arrangement, choice of suitable transmission ratios between the sun gears 29, 32 and the planet gears 31 makes it possible to sew a single stitch at a bent or corner of the sewing path or pattern.

Where it is desired to produce a sewing path or seam comprising bents of varying sense or direction, a twindifferential drive may be employed in place of the singledifferential drive mechanism of FIG. 3. A stencil drive of this type embodying a twin-differential 74 is shown by FIGS. 5 and 6. According to the latter, operation of the stencil is derived from the driving motor 75 of the sewing machine, in contrast with the separate stencil drive motor 13 shown by FIG. 4. With specific reference to FIG. 6, the motor 75 drives, by way of a belt 76 or equivalent transmission means and a magnetic clutch 77, an input bevel gear 78 meshing with two output bevel gears 79 and 80 which are connected, respectively, with the driving halves or members 81, 82 of a pair of further magnetic clutches 83 and 84. The bevel gears 79, 80 and associated clutch members are freely rotatively mounted a worm shaft 85 which is rigidly connected with the driven halves or members 88, 89 of the clutches 83, 84. One end of the worm shaft 85 is fitted with a braking magnet 90, while the opposite end of said shaft carriers a worm 91 being in meshing engagement with a worm gear 92.

Mounted upon the shaft 93 of the worm gear 92, FIG. 5, is a first spur gear 94 which meshes with a further spur gear 96 being freely rotatively supported by a mounting plate or frame 95. Fixedly connected to each of the gears 94, 96 is one of a pair of further coaxial bevel gears 97, 98 which serve to rotate, via bevel gears 99, 100 and in opposite directions, a pair of first (outer) sun gears 102, 103 of the twin-differential 74. An inner sun gear 108 meshes with planet gears 104 being freely rotatively mounted upon a planetary carrier 107 which has affixed thereto a bevel gear 106 of the right hand section of the twin-differential 74 of FIG. 5. Sun gear 108 is rigidly mounted upon a shaft 110 to one (inner) end of which is secured a bevel gear 111, while the opposite end of the shaft 110 is fitted with a braking magnet 112. The bevel gear 99, sun gear 102 and the planetary carrier 107 are all rotatively mounted by the shaft 110.

In a similar manner, the outer sun gear 103 of the left hand section of the twin-differential according to FIG. 5 meshes with planet gears 114 being rotatively supported by a planetary carrier 115 to which is afiixed a bevel gear 116. The planet gears 114 are in meshing engagement with a second (inner) sun gear 119 mounted upon a shaft 118 which carries a bevel gear 120 at one (inner) end thereof, while its opposite (outer) end is fitted with a braking magnet 121. The bevel gear 100, sun gear 103, planetary carrier 115 and the bevel gear 116 are all freely rotatively mounted upon the shaft 118.

Both bevel gears 111 and 120 mesh with a bevel gear secured to the lower end of a rockshaft 124 passing through the table 1 of the sewing machine and having secured to its upper end a guide roller carrier 126. A first guide roller 128 is freely rotatively suspended from a supporting block or member 129 which is secured to the carrier 126 by means of a flat spring 130, to allow of radial deflection of said block and the roller 128. Disposed diametrically opposite and in axially displaced relation to the guide roller 128 is a further guide roller 132 being rotatively suspended from a further supporting block or member 133 which is connected to the carrier 126 through a flat spring 134 in a manner similar to the mounting of the member 129.

The bevel gear 116 carried by the planetary carrier 115 meshes with a further bevel gear 136 affixed to the lower end of a first hollow drive shaft 137 concentrically mount ed upon the rockshaft 124. Secured to the upper end of shaft 137, at a position adjoining the guide roller 128, is a first stencil driving roller 138. Besides, bevel gear 106 affixed to the planetary carrier 107 meshes with a bevel gear 140 which is secured to the lower end of a second hollow drive shaft 141 being concentrically mounted upon the first-drive shaft 137. The upper end of the drive shaft 141 has aflixed thereto, at a position adjoining the guide roller 132, a second stencil driving roller 142 which has a lower conical extension 143.

FIG. 7 shows an exemplary stencil for the sewing of collars and suitable for use in conjunction with the driving mechanism shown by FIGS. 5 and 6. More particularly, the stencil 145 as shown comprises a base plate 146 and a plurality of consecutive guide strip sections or components 147, 148, 149, 150 and 151 disposed along and on the opposite sides of the sewing path or pattern 152 depending upon the direction or sense of the bents 156, 157, 158, etc. in respect to said path, for the purpose as will become further apparent as the description proceeds. More particularly, in the example shown the partial guide strips or sections 147, 149 and 151 conform with the bents of the path 152 in one direction, and the partial strips or sections 148, 150 conform with the bents of the path 152 in the opposite direction, respectively.

The operation of the twin-differential stencil drive described in the foregoing is essentially similar to the operation of the single-differential drive according to FIGS. 2, 3 and 4. At first, the magnetic clutches 77 and 83 are energized, while simultaneously releasing or de-energizing the braking magnets 90, 112 and 121. Assuming that the scanning of the stencil 145 is started at point 155, FIG. 7, the rockshaft 124 will be arrested, for reasons explained and described hereinbefore, during the stencil movement or displacement along its first linear portion or section 147. As a consequence, the inner sun gears 108, 119 of the twin-differential 74 are locked via the bevel gear 125 and bevel gears 111, 120, whereby to cause the planet gear carriers 107, 115, rotating in opposite directions, to drive the rollers 138, 142 also in opposite directions, that is, in such a manner that the driving roller 142, FIG. 7, rotates in anti-clockwise direction and that the driving roller 138 rotates in clockwise direction in the example illustrated and described.

During the latter operation, the flat spring 134 acts to urge the guide roller 132 and partial guide strip 147 against the driving roller 142, while the driving roller 138 remains idle during this operation due to the absence of a cooperating guide strip within the stencil section 147. Upon reaching the bent 156 the inner sun gear 108 comes 1nto action briefly, in the manner described and explained hereinbefore, whereby to cause the carrier 126 to be rotated or deflected, via the bevel gears 111, 125 and rock shaft 124, in clockwise direction and to an extent such that the line connecting the center points of the rollers 132, 142 consecutively assumes a position normal to the tangent of the bent and to the second straight portion or section 147 of the stencil, whereupon the roller 142 continues to rotate by way of bevel gears 106 and 140.

At the point or position of engagement by the roller pair 128, 138 of the stencil portion intermediate the bents 156 and 157, the roller pair 128, 138, cooperating with the stencil section 148 of and being biased by the spring 130, assumes the drive of the stencil after both driving and guide roller pairs have been in brief simultaneous engagement with both stencil sections 147, 148 as a result of the overlap of the adjoining ends of the sections as shown in FIG. 7. As a consequence, the driving roller 138 is now rotated in clockwise direction via the planetary carrier 145 and bevel gears 116, 136 and as a result of the locking of the sun gear 119. Upon reaching the bent 157, the driving roller 138 and drive shaft 137 are arrested, whereby, due to the continued drive of bevel gear 100 and the outer sun gear 103, the inner sun gear is now caused to rotate, thus in turn causing the rockshaft 124 to be deflected or rotated in anti-clockwise direction by way of the shaft 118 and bevel gears 120, 125, until the plane including the axes of rollers 128, 138 assumes a position normal to the tangent of the stencil section 148 upon leaving of the bent 157 by the rollers 128, 138. Subsequently, the rockshaft 124 is again arrested, whereby to cause a renewed clockwise rotation of the drive shaft 137 and driving roller 138 via the planetary carrier 115 and bevel gears 116, 136.

Between the bents 157 and 158, the roller pair 132, 142 again assumes the drive of the stencil 145 and the described mutual operation between the parts is repeated, in the manner readily understood from the foregoing, until reaching the end 160 of the sewing path 152.

By changing from the magnetic clutch 83 to the clutch 84, FIG. 6, the direction of rotation of the twin-differential 74 may be reversed. This makes it possible, for instance, after mounting of a new sewing goods frame, to sew in the reverse direction, that is, from the point 160 to point 155, FIG. 7. Upon reaching the end positions 155 and 106, the braking magnets 112, 121 are energized, to ensure the stoppage of the frame in the proper positions, such as for the exchange of one stencil for another. De-energization of clutch 77 and energization of braking magnet 90 makes it possible to finally arrest the stencil drive.

In the foregoing, the invention has been described in reference to a specific illustrative device. It will be evident, however, that variations and modifications, as well as the substitution of equivalent parts and elements for those shown herein for illustration, may be made without departing from the broader scope and spirit of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.

We claim:

1. Stencil drive mechanism of the type described comprising in combination:

(1) a strip-like stencil including at least one bent,

(2) a stationary driving roller engaging the concave side of said stencil in respect to said bent,

(3) a guide roller arranged to engage the convex side of said stencil in respect to said bent, said guide roller located opposite to and with its axis disposed parallel to the axis of said driving roller,

(4) operating means to rotate said guide roller within an arcuate path of its axis concentric with the axis of said driving roller, and

(5) a differential drive to operate said stencil comprising (a) a pair of sun gear members,

(b) a carrier member rotatively supporting a plurality of planet gears in meshing engagement with said sun gear members,

(c) a power source to drive one of said members,

and

(d) a pair of coupling means each operably connecting one of the remaining members of said drive, respectively, with said driving roller and said guide roller operating means, to rotate said driving roller about its axis in one direction and to rotate said guide roller within said path in the opposite direction.

2. In stencil drive mechanism as claimed in claim 1, including means to resiliently urge said guide roller against said stencil and said driving roller.

3. In stencil drive mechanism as claimed in claim 1, said differential drive including an internally threaded outer sun gear and an externally threaded inner sun gear, and said carrier being concentric with and disposed between said outer and inner sun gears.

4. In stencil drive mechanism as claimed in claim 3, said outer sun gear being driven by said power source and said carrier and inner sun gear being operably connected, respectively, to said driving roller and guide roller operating means.

5. In stencil drive mechanism as claimed in claim 3, said outer sun gear being driven by said power source and said carrier and inner sun gear being operably connected to said driving roller and guide roller operating means through, respectively, a hollow drive shaft and a rockshaft concentric with and mounted within said hollow shaft.

6. In stencil drive mechanism as claimed in claim 5, said rockshaft passing beyond the upper end of said hollow shaft and having secured to it a lever having a radial slot, and a springloaded sliding block disposed within said slot and rotatively supporting said guide roller.

7. In stencil drive mechanism as claimed in claim 5, said rockshaft passing beyond the upper edge of said hollow shaft and having secured to it a lever, a supporting member rotatively supporting said guide roller, and resilient means connecting said lever and said supporting member, to allow of relative radial movement therebetween.

8. In stencil drive mechanism as claimed in claim 1, said power source consisting of an electric motor, a control switch for said motor, and actuating means for said switch operable by depression of said stencil, to start and stop said motor at predetermined stencil positions.

9. In stencil drive mechanism as claimed in claim 1, said stencil consisting of at least two discrete consecutive sections including bents of opposite curvature, a pair of separate driving and guide roller pairs each arranged, respectively, for cooperation with one of said stencil sections, said differential drive arranged to operate one of said driving and guide roller pairs in one direction, and a further differential drive similar to said first drive and arranged to operate the other of said driving and guide roller pairs in the opposite direction, said stencil sections being spaced by distances equal to the diameter of the driving rollers of said pairs and arranged with the end zones of one section overlying the end zone of the other section, whereby to effect an automatic transition of the stencil drive from one to the other section of said stencil.

10. In stencil drive mechanism as claimed in claim 9, said stencil sections and cooperating driving and guide roller pair being disposed edgewise in spaced relation to one another.

11. In stencil drive mechanism as claimed in claim 9, including a common drive motor and multiple motiontransmitting means therebetween and the inputs of said differential drives, to rotate said drive in opposite direc tions.

References Cited UNITED STATES PATENTS 3,276,405 l()/ 1966 Scholl 112-2 FOREIGN PATENTS 477,417 12/1953 Italy. 1,044,302 6/1953 France.

FRED C. MATTERN, JR., Primary Examiner.

W. S. RATLIFF, JR., Assistant Examiner.

U.S. Cl. X.R. 74665; 1122 

